It is a 2D version of Horbach's and Keele's design. But they never showed a version with a constant directivity in the highs. The tweeter is always the problem, because it is alone and has no partner. And its bandwidth is higher than the other ways.
When doing 1D with waveguide the distance between the mid-high-drivers is too large. It doesn't work. So I switched to 2D and increased the grid depth of the mid-high-drivers to shift side lobes to higher frequencies.

I failed to design a pseudo-coaxial speaker that has a wider directivity. And I failed to design one with different horizontal and vertical directivities.

But I tried to separate horizontal and vertical with a ribbon driver and a horizontal waveguide. It doesn't work that good, because ribbons can not be crossed deep enough. And plane wave formers for compression drivers are usually too large. But the concept could still be promising.Read the documentation here (again in German).

A directional tweeter (waveguide or ribbon) always has larger dimensions than a dome. And this increases the distance of the surrounding drivers (and shifting lobes down in frequency etc.). The whole concept is based on a certain distance between the drivers. A directional tweeter is contrary to the concept.

Not completely. It gets a bit worse, but not much. I have only simulations yet and have to measure the diagonal direction on the prototype.

Quote:

Originally Posted by Boden

Superb project! How have you determined the exact placement of woofs and mids? Or should I ask: what software did you use to come the the final design?

Thanks! I used ABEC to determine the best positions, sizes and crossover points of the drivers. Usually the prototypes were build after a promising simulation that I designed after an idea. And it always fit good with that.

I'm a bit proud of the optimized alignment of prototype 7. It looks weird and chaotic, but there is a system behind it. I considered the horizontal and vertical directions indepenently.
To shift the side lobes to higher frequencies the drivers must be placed near and equally spaced. You can consider the grid as "weighted". If one driver is on one of the fixed positions the weight is 1. If there are two the weight is 2. All positions must be equal weighted to get the best result.
Prototype 7 is the result to get a high density grid of midrange drivers and to weight all drivers equally in both directions.

With this trick I was able to shift the side lobes to >5 kHz. This is important, because to shape directivity you need both ways to widely overlap in frequency.

Anyway, I skipped the 2-way design and switched to 3-ways. I found that the big horn didn't sound as good as the small one. Sibilants sound much better with the current prototype.